pfsense! http://www.pfsense.org/ you can put pfsense or its sister project, m0n0wall (scaled down version), on any machine or an embedded machine. Really extensive feature list, reduces costs to hardware.

There's also DD-WRT (which you install onto commercial appliances, then overwrite their firmware), but I haven't tried it out yet.

Didn't upvote the article, you're absolutely right about it being fluff.